Targeted Modulation of Competitive Active Sites toward Nitrogen Fixation via Sulfur Vacancy Engineering Over MoS2

作者：Fei, Hao; Liu, Ruoqi; Wang, Jian; Guo, Ting; Wu, Zhuangzhi^*; Wang, Dezhi^*; Liu, Fangyang^*

来源：Advanced Functional Materials, 2023, 33(36).

DOI：10.1002/adfm.202302501

• hydrogen evolution reaction
• molybdenum sulfide
• nitrogen reduction reaction
• selectivity
• sulphur vacancies

Electrocatalytic nitrogen reduction reaction (NRR) offers an environmentally benign and sustainable alternative for NH3 synthesis. However, developing NRR electrocatalysts with both high activity and selectivity remains a significant challenge. Guided by the density functional theory (DFT) calculations and further verified by the experiment, a modulated MoS2 with well-controlled S vacancies (MoS2-Vs) is prepared as an excellent electrocatalyst for NRR, where both the activity and selectivity of NRR mightily rely on the S-vacancy concentration. The optimized catalyst (MoS2-7H) in a suitable S-vacancy concentration (17.5%) is empowered with an excellent NRR activity (NH3 yield rate: 66.74 mu g h(-)(1) mg(-)(1) at -0.6 V) and selectivity (Faradic efficiency (FE): 14.68% at -0.5 V). Further mechanistic study reveals that the NRR performance is powerfully concentration-dependent since its activity is enhanced due to the S-vacancy-strengthened N-2 adsorption and reduced reaction energy barrier. Simultaneously, its selectivity is synchronously improved by the steadily enhanced NRR activity and inversely suppressed hydrogen evolution reaction through limiting H-2 desorption kinetics, which sets it markedly apart from other reported defective MoS2-based catalysts.